The present invention relates generally to filters, and more particularly to pleated air filters for use in residential air filtration and industrial air filtration.
Pleated air filters are normally produced by taking a non-woven fabric and combining that fabric with a wire or some other support to maintain the pleat in the fabric while air passes through the unit. The wire is normally attached to the fabric by an adhesive, pressing the fabric to the wire to achieve a laminated structure. The laminated structure is then pleated or formed into an accordion like structure which is then placed into a fiberboard or cardboard frame for use in an air handling unit. The use of wire supported pleats, however, requires additional equipment needs and also creates environmental concerns regarding the disposal of used filters.
As an alternative to the wire supported media, self-supporting pleated filter media has been developed. For example, U.S. Pat. No. 5,167,740 to Michaelis et al ("Michaelis")., discloses a method of making a filter insert of non-woven material in the form of a pleated pack which is self-supporting and consists of thermally weldable non-woven material. The pleats in Michaelis are formed by folding the material to form the pleats and welding the edges of the material together.
Also, for example, U.S. Pat. No. 5,456,836 to Jeffery, et al. ("Jeffery") discloses a self supporting filter element made of a precursor fiber web containing heat-shrinkable fibers or binder fibers or both. Jeffery teaches the shaping of the filter element and then the submitting of the element to a rigidification process.
The apparatuses of Michaelis and Jeffery, however, require additional equipment for processing and, because of their dimensions and rigidity, they require more attention and space, and, thus, require increased shipping cost.
Clearly, there is room for improvement in the art.